Gwendolyn "Gwen" Tennyson is a Human/Anodite hybrid Plumber, the paternal first-cousin of Ben Tennyson, and (along with Kevin Levin) a front-line member of his team. Gwen was first introduced when her parents sent her on a summer-long road trip with her Grandpa Max and her cousin Ben. She has, as Verdona refers to it, "The Spark".
In Omniverse, 16 year old Gwen still has her ponytail but with a different style. She now wears clothes similar to her Alien Force outfit minus the leggings. She also now has freckles.
Later on she has shorter hair, a light blue shirt with her cat logo on her shirt, a blue skirt and wears glasses.
11 year old Gwen in Omniverse wears the same outfit from the original series she has not changed much.
Appearances16 year-old Gwen
- The More Things Change: Part 1 (first appearance)
- Many Happy Returns
- Ben Again
- Showdown: Part 2
- The Frogs of War: Part 2
- Mud is Thicker Than Water
- For a Few Brains More
- A Jolt from the Past
- Trouble Helix
- It Was Them (cameo)
- Of Predators and Prey: Part 2
- Ben Again
- Mud is Thicker than Water (flashback)
- Gwen and Kevin leaves for college in Ben 10: Omniverse.
- Gwen and Kevin still remains in a relationship.
- Gwen wears her Alien Force outfit in Omniverse.
- Gwen's new look resembles Velma Dinkley from the Scooby Doo series.